Dyeing of cellulose acetate, artificial silk, films, and the like



Patented Apr. 8, 1924.

UNITED STATES PATENT OFFICE.

MAURICE ERNEST BOUVIER, OF LYON, FRANCE, ASSIGNOR, BY MESNE ASSIGNMENTS,TO LA SOCmTE POUR LA FABRICATION DE LA SOIE RHODIASETA, OF PARIS,

FRANCE, A CORPORATION OF FRANCE.

DYELNG OF GELLULOSE ACETATE, ARTIFICIAL SILK, FILMS, AND THE LIKE.

No Drawing.

To all whom it may concern:

Be it known. that I, MAURICE ERNEST BOUV'LER, residing at Lyon, France,a citizen of the Confederation of Switzerland, have 6 invented certainnew and useful Improvements in or Relating to Dyeing of CelluloseAcetate, Artificial Silk, Films, and the like, of which the following isa specification.

This invention relates to the dyeing of 10 cellulose acetate films,threads or the like, and is an improvement in or a modification of theinvention described in Letters Patent of the United States, No.1,366,023, granted to Edmond Prince under date of January In thispatent, a process is described by which cellulose acetate films, threadsor the like are rendered capable of being dyed by being treated withsolutions of salts of alkali metals to which alkali has been added.

In the said patent, only one example has been given, in which a solutionof sodium chloride is used, to which caustic soda has been added. Wehave found that the caustic alkali can be replaced by a salt with analkaline reaction (carbonate, borate, silicate, tribasic phosphate,etc.) adapted to act as an alkali in the saponification of the acetate,the quantity of said salt being less than is required to make a one percent solution.

Example.

A hank of 100 grammes of cellulose acetate silk is plunged into a bathof 2 litres,

Application filed April 25, 1922. Serial No. 556,423.

containing 800 gr. of crystallized sodium sulphate (350 gr. SO,Na and 17gr. of sodium carbonate.

The hank is smoothed in the bath, gradually heated to 85 C. until paperimpregnated with phenolphtalein is no longer colored by contact with it,this being obtained after a treatment of from 30 to minutes.

The silk is then withdrawn from the bath and dyed.

lVhat I claim and desire to secure by Letters Patent is 1. A process fortreating cellulose acetate films, silk and the like previous to dyeing,consisting in treating the cellulose acetate with a relativelyconcentrated solution of neutral salts of alkali metals to which a saltwith an alkaline reaction, adapted to act as an alkali in thesaponification of the acetate is added in quantity less than is requiredto make a 1 per cent solution.

2. The process of preparing cellulose acetate for dyeing, which consistsin immersing the same in a bath containing sodium sulphate and sodiumcarbonate in the proportions of fifty to one, and heating the bath to atemperature of approximately 85 C. for thirty to forty-five minutes.

In testimony whereof I have signed my name to this specification.

MAURICE ERNEST BQUVIER.

Witness JULIAN KEMBLE SNEDLEY.

